Patent Application
20080006435
Further objects and advantages of the invention will be apparent from the following description and appended claims, reference being made to the accompanying drawings forming a part of the specification, wherein like reference characters designate corresponding parts in several views.
With increasing electronic content in automobiles there is an ever growing need for miniaturizing the size of the cables that provide resistance to physical abuse and provide resistance to flame and automotive fluids among other requirements to be met for the automotive industry such as ISO 6722. It has been found to be particularly desirable to utilize an insulated non-halogenated, heavy metal free vehicular cable containing a copper based metal wire that has a diameter of at least about 0.1 mm or more and an outer insulation covering the length of the inner core comprised of a thermoplastic polyphenylene ether composition which has no halogen or heavy metal added thereto.
Definitions:
By “non-halogenated” is meant that the polymeric material that is utilized has no halogen material that is added to the composition, as a desirable component of the composition.
By “heavy metal free” is meant that no heavy metal such as mercury, hexavalent chrome, cadmium, lead and the like are added to the metal core, as a desirable component of the metal composition.
By “copper based metal” is meant that the metal wire is comprised of greater than 50% by weight of the metal being copper, or copper alloyed with other metal components as is well known in the industry yet maintaining suitable electrical conductivity. Well known copper based alloys may be used such as HPC-80EF, trademark Phelps Dodge.
By “polyphenylene ether” is meant a thermoplastic polymeric material which is commercially available and generally are polymers of monohydroxy aromatic materials. Other readily available materials are 2,6-xylenol or a 2,3,6-trimethylphenyl and polymers thereof. Polyphenylene ether (PPE) is also known as polyphenylene oxide (PPO) and is described in the literature. See U.S. Pat. Nos. 3,306,874, 3,306,875; 3,257,357; and 3,257,358, which are herein incorporated by reference.
Frequently polyphenylene ether materials are a blend of other thermoplastic or cross-linked ethylenically unsaturated materials such as polyolefinic materials, styrene or styrene butadiene or polyacryamide and the like. These materials are commercially available such as Noryl, Luranyl, Ultranyl or Vestoblend, trademarks of GE. Some materials that may be utilized include Noryl WCV072, WCV072L-111, and the like of GE.
It has been found that the ultra thin cable and cable wall that is utilized in the present case even at a small cross section of 0.1 mm2 give a very satisfactory result in abrasion cycling tests such as that called for in ISO-6722.
The cross sectional area of the copper wire can range from about 0.1 to about 3 square millimeters, such as 26 AWG to 12 AWG, alternatively 0.13 to 1.5 square millimeters.
The insulated cable of the present invention is prepared utilizing normal well known commercially available equipment where the desired polyphenylene ether polymer is fed to an extrusion machine where the molten viscous polymer is passed through a die, as shown in
Turning now to a description of the drawings.
During the extrusion process of the insulated vehicular cable 10, the copper based core is fed through the middle of die 20 entering the back end 22 of the die and exiting from the die at 24. The die has a central portion 26 through which the copper based wire 14 passes. The hot viscous PPE will be passed into the space 28 at the entrance end 22 of the die 20 and proceeds to envelop the copper wire. The die begins to narrow at 30 as PPE is extruded with the copper based wire passing from 30 through exit 24 of the die. At the exit 24 of the die, the insulated vehicular cable 10 of the present invention is obtained. The cooling process as described above and the packaging of the cable follows thereafter.
The diameter of the insulated vehicular cable 10 of the present invention can vary substantially. A cable diameter that has been found useful is between 0.85 and 0.92 mm in case of 0.13 mm2 cable. Other dimensions of an insulated vehicular cable would be one that has approximately 0.13 square millimeters of wire as its cross sectional area but which is used to form the embodiment shown in
As indicated above a wide variety of commercially available extruding equipment may be utilized such as an extruder identified as BMD60-24D or a Nokia Maillefer, and the like.
The die utilized in the present invention may be manufactured from a wide variety of commercially available materials such as D2 hardened tool steel.
Following the procedures outlined in ISO-6722, scrape abrasion resistance using 7(N) load and 0.45 millimeter needle was used on three sets of cables, the first being compressed halogen free cable ISO ultra thin wall cable referred as CHFUS, the second ISO thin wall cable referred as HFSS and the third ISO thick wall cable referred as HF. The test results are identified in tables 1 and 2 below.
Following the procedures outlined in ISO-6722 a number of tests were so performed where the thickness of the copper wire varied as well as the diameter of insulated polyphyenelyene ether varied as is shown in tables 3-4.
Following the procedures outlined in ISO-6722 a number of tests were so performed where the cross sectional area of the copper wire varied as well as the diameter of insulated polyphyenelyene ether varied as is shown in tables 3-4.
Listed below in Table 5 is a measurement of the PPE toughness for ISO 6722 needle abrasion cycles to failure compared to material thickness using a 7-N load and 0.45 millimeter needle.
Current PVC tape construction has thicknesses for backings of 0.09-mm and above. This thickness for PVC is required to provide a minimum amount of toughness or abrasion protection while also providing sufficient tensile and tear strength that PVC tape may be applied. Given data from Table 5 and the current film thickness, one can conclude that significantly thinner backings are possible with PPE. PPE backings as thin as 0.03-mm or less could be achieved and still maintain equivalent abrasion protection and toughness to the current PVC backings. Given this potential for reducing backing thickness and specific gravity differences, a weight reduction of 75% seems reasonable with a PPE tape compared to a PVC tape.
With thinner backings, greater linear length of tape can be put up on each roll of tape. This is important for handling in and application of tapes on substrates or wire harnesses. The physical dimensions of a tape roll are limited to physical constraints with a manufacturing operation and by human ergonomic issues. Too large of roll diameters are ergonomically awkward and uncomfortable for continuous daily use. However with thinner tapes, longer roll lengths are possible while still maintaining an acceptable roll diameter. This then benefits the manufacturing by minimizing the number of times workers must retrieve new rolls. For an automotive wire harness manufacturing, a new roll may be required as often as once or twice per wire harness. Also benefit is achieved in shipping since more tape can be shipped for a given container volume.
In addition to being halogen free and tougher than PVC, PPE also offers ability to be used in higher temperature environments. Currently PVC may be rated for use at 105° C. which limits it to select exterior automotive applications. Many of the applications however, such as engine and chassis require temperature ratings of 125° C. and above. This is feasible with PPE which has been rated to 125° C. for continuous use and with excursions to 150° C. and above.
PPE backings could be used with any desired pressure sensitive adhesive available today. This would include natural rubber, natural rubber/synthetic rubber blends, synthetic rubber, acrylic, or other adhesive systems.
Turning now to
There are a wide variety of pressure sensitive adhesives well known in the trade for applying such adhesives to thermal plastic materials. Such adhesives can be natural rubber, synthetic rubber, cross-link acrylics or blends of these polymers. Formulated adhesives may be include Morscic, Acronyl or Duro-Tak that are particular types of acrylic adhesive to be used to coat the bottom portion of the PPE material. The pealable tape can be a variety of materials such as paper, cellulose or any plastic film materials that can be coated with a release layer such as a silicone coating well known in the art.
